OK...
Thats the correct vision of the nature of man.
No question mankind is fallen.
In contrast, the source of all ideological error is the assumption that man is basically good.
That's the source of *all* ideological error? I could see it being the source of most anthropological error, but you really can't think of *any* ideological error that isn't directly descended from that one error?
I’ve actually done the research for various presentations.
Starting from Sowell’s Conflict of Visions, where he states the dichotomy of (his terms) the “constrained” vs the “unconstrained” view of man,
I took it back to where THOSE views of man come from - the nature of man, fallen and flawed, or “basically good” and perfectible.